Best ETF overlap checkers, compared on what they measure

Updated 24 August 2026

Most "best overlap tool" lists rank on opinion. This one ranks on what you can check yourself in about ten minutes: whether the tool returns a number at all, whether that number is a share of weight or a count of holdings, whether it reports the two funds separately, and what it costs. Every cell was read on the provider's own site.

Checked on each provider's own site · monthly price where published · an em-dash means the tool does not offer the capability at all, so the column does not apply.

What to look for in an overlap checker

• A number, not a picture. Two lists side by side is not a measurement.
• By weight, across every holding — not a count of shared names, and not the top ten.
• Both directions, because they are usually different.
• Without an account, if you only want to check one pair.

The two things a checker has to get right

Weight, not count. Two funds can share 90 of their holdings and almost none of their money, if the shared names are the small positions in both. Overlap that means anything is the share of each fund's weight that lands in the same companies.

Both directions. Overlap is not one number. A focused fund can sit almost entirely inside a broad one while being a small slice of it, and reporting a single symmetric figure hides which fund contains which — which is the part that decides whether adding the second fund changes anything.

QQQ and VTI are the clearest case: 96.3% of QQQ's weight sits inside VTI, while only 47.7% of VTI is QQQ. A single symmetric figure for this pair reads 47.7%, which tells you they share something and hides which one contains the other.

Where ETF Copilot is and is not the right tool here

For checking one pair, ETF Research Center's tool is at least as good and adds sector drift, which we do not publish. What ETF Copilot does differently is scale: every pair in the universe is updated daily rather than on request, grouped by what the relationship actually is — funds that are effectively the same, funds where one sits inside the other, funds that look alike and are not — so the pairs worth knowing about surface without being asked for by name.

If you already know which two funds you are comparing, either works. If you want to know which pairs in a list of holdings are duplicating each other, a per-request tool cannot answer that.

Which one to use, by what you are trying to do

Check one specific pair

ETF Research Center — overlap by weight, both directions, plus sector drift, without an account. The full list of shared holdings needs a free login.

Find which pairs among many funds duplicate each other

ETF Copilot — every pair is updated daily and grouped by relationship, so you do not have to know which pair to ask about.

See whether two funds move together rather than hold the same things

Portfolio Visualizer — asset correlations. A different question from overlap, and sometimes the one you actually meant.

Compare two funds' basics side by side

Stock Analysis — fees, size, returns and top holdings in one view, free. It will not tell you how much they share.

How much do two ETFs overlap?

It depends entirely on the pair, and the honest answer is a range rather than a number. Among the funds ETF Copilot covers, a small number of pairs are effectively identical — above 99% of each fund's weight in the same companies — while most pairs share very little. The figures above give the current distribution.

Is high overlap between two ETFs a problem?

It is a fact to know rather than a fault. Two funds with high overlap are one position held twice, with two expense ratios, and whatever diversification was intended by holding both is not there. Whether that matters depends on what the rest of the portfolio holds, which no overlap tool can see.

What is the difference between overlap and correlation?

Overlap measures shared holdings; correlation measures returns moving together. Two funds with no shared holdings can be highly correlated if they hold similar kinds of company, and tools that offer correlation instead of overlap — Portfolio Visualizer, for example — are answering the second question, not the first.

How was this compared?

Each tool was opened on its own site and asked for the overlap between two large US equity ETFs, logged out. A tool counts as quantifying overlap if it returns a number for how much the two funds share; as weighted if that number is a share of fund weight rather than a count of holdings; and as both-directions if it reports the two funds separately. Prices are the advertised monthly rate on the provider's own pricing page, or the annual rate divided out where only that is published. A capability the tool does not offer at all is an em-dash rather than a "no", because the column does not apply.

See the pairs that overlap most →

ETF Copilot reports data factually. Nothing on this page is investment advice, a recommendation, or a forecast of returns. It describes how to read fund data, not what to do with it. Third-party capabilities were checked on each provider's own site on 24 August 2026.